Conventionally, as a light source for vehicle-mounted headlight, an electric lamp employing a tungsten filament as a light emitting body, an electric-discharge lamp emitting light through arc discharge, or the like is used.
Further, recently, in place of electric lamps and electric-discharge lamps, light emitting diodes (LEDs) have become widespread. Because LEDs have a long life, can ensure brightness needed for headlights with low power consumption, and can stabilize brightness under a simple control operation of supplying a constant current thereto, LEDs are suitable for use as light sources for vehicle-mounted headlight. Further, LEDs have many variations in size and brightness, so that the number of light sources used to form a light distribution of a headlight, and the shape of each of the light sources can be selected freely. Therefore, a headlight with high originality or a reduced size headlight which, conventionally, was not able to be implemented because of restrictions on the number of light sources or their shapes can be implemented.
In each of Patent Literatures 1 to 3, a headlight having alight source, a reflector for reflecting light emitted by the light source, and a projection lens for projecting the light reflected by the reflector onto an area ahead of a vehicle is disclosed. In particular, in each of Patent Literatures 2 and 3, a headlight in which an LED is used as a light source, and a reflector and a projection lens being integrally formed of a transparent material is also disclosed.